Simulation Of Thermal Performance Research Articles

Integration of Photovoltaic Cells in Building Shading Devices:

This study focuses on the thermal performance simulation of the CSERS administrative building. It proposed the integration of shading elements on the south façade of the building to enhance thermal comfort for office occupants. These shading elements incorporate photovoltaic cells, displaying the potential of utilizing photovoltaic in external shading devices. The main objective of this approach is effectively address issues related to high internal temperatures and excessive solar radiation exposure. Furthermore, it ensures the preservation of key functions of the building envelope, such as thermal insulation, provision of natural lighting, and prevention of internal thermal glare. Comparative analysis is conducted between the building equipped with shading devices and the one without, with a focus on measuring the total electrical energy generated by the photovoltaic panels. Simulation programs such as SketchUp and EnergyPlus are utilized for this purpose. The results of the simulations reveal that strategically designed shading on south-facing windows leads to 17.15% reduction in annual heat gains transmitted to the building. In addition, the integration of photovoltaic shading devices demonstrates outstanding performance characteristics, contributing a productive capacity of around 5916.388 MW/h to the building. This integration effectively harnesses solar energy to improve the indoor environment of the building.

Defining the calibration process for building thermal performance simulation during the warm season: a case study of a single-family log house

ABSTRACT The study aimed to develop a holistic, evidence-based calibration strategy and define a hybrid step-by-step methodology for building thermal simulations during the warm season. The methodology was demonstrated using the thermal performance of a naturally ventilated single-family log house in a temperate climate. The calibration process was supported by on-site measurements of indoor thermal conditions and occupant behavioural reports between April and July. Hybrid calibration methodology combines statistical indicators, such as NMBE, CV(RMSE), and R 2, and a graphical evaluation of the deviation between the simulated and measured values. After 28 proposed calibration steps, a final calibrated model predicted the actual thermal response of the log house with an accuracy of ±1°C at 71.6% or ±2°C at 98.4% of the considered time. The results showed that occupant-related information, material properties and infiltration rates are crucial to improving the reliability of building thermal models. Moreover, in the calibration process of log houses, appropriate determination of building envelope materials’ thermal conductivity, wood's solar absorptivity, and airtightness showed high importance. The study highlights the importance of calibration for reliable building thermal models, specifically in overheating prevention simulations.

Thermal performance simulation of parabolic trough collector with ternary nanofluid flows and half-star-shaped fins inserts in different receivers

Thermal performance simulation of parabolic trough collector with ternary nanofluid flows and half-star-shaped fins inserts in different receivers

Fast assessment method of annual energy consumption for DSF and SSFs

Double skin façade (DSF) is widely used to improve energy efficiency in buildings. Many studies have analyzed the thermal performance of DSF and single skin façade (SSF) on just standard days or typical moments. However, in order to more accurately analyze its energy-saving effect, its annual thermal performance should be evaluated. For achieving this, a large number of simulations are needed and it is extremely time consuming and complicated. This study provides a new fast calculation method for annual thermal performance and energy consumption of DSF and SSFs. Firstly, based on CFD technique, a simulation method for obtaining indoor temperature of DSF during whole year was established, and the results were verified through experiments. Then, a new simulation calculation method for heating and cooling periods was established, thereby completing annual thermal performance simulation of different facades. Finally, based on total heat gain/loss of each facade, the energy consumption of mentioned facades was calculated, and facades’ various performance can be seen for entire year. As an overall result for Beijing located in cold region, by considering whole year energy consumption, DSF plays as the best one with 18 % energy saving in the whole year compared to the second one which is 3 glazing exterior shading SSF; however, this SSF can save 37 % building area compared to DSF. The result of this study can be useable for other cities with same climate as the Beijing. The analyze method proposed in this study is useable for optimizing building facades in different climates.

Numerical simulation of thermal performance based on cogeneration low carbon heating unit manufacturing

The renewable energy complementary cogeneration system has broad application prospects in the field of regional comprehensive energy utilization. The author proposes a trough solar assisted biomass cogeneration system, which uses medium and low temperature trough solar energy to heat conduction oil, drives absorption heat pump to preheat water in the heating network, saves heating steam extraction and increases power output under the condition that biomass fuel and heat supply remain constant. The EBSILON professional software was used to model and simulate the case unit and integrated system, and based on this, thermodynamic characteristics such as system energy flow and energy loss were analyzed. The results indicate that: under the design condition, 1.78 MWh of solar power can be generated, the photoelectric efficiency is 20.06%, and the photoelectric conversion efficiency can reach 21.60%. Hourly simulation analysis of the whole heating season shows that the total solar power generation generated in five months of the heating period is 1124.30 MWh, and the average photoelectric efficiency is 16.49%.

Numerical simulation of thermal performance of cold plates for high heat flux electronics cooling

High heat flow density electronic components need cooling plates with strong heat exchange capacity to maintain temperature balance. To obtain better cooling performance, four different flow channel types of cooling plates are designed, including an S-type channel, Z-type channel, mosaic channel and double-layer channel. The maximum temperature of the cooling plate, outlet temperature and pressure drop under different working conditions and coolant are analyzed by numerical simulation. The simulation results show that the double-layer channel design can effectively enhance the heat transfer effect of the cooling plate and reduce the pressure drop. The maximum temperature of the cooling plate of the double-layer flow channel is 6.88 ?C lower than that of the Z-type flow channel. Moreover, increasing the inlet flow rate and lowering the coolant inlet temperature can improve the cooling performance of the cold plate, but increasing the inlet flow rate will lead to an increase in the pressure loss of the cold plate. When the coolant of the dou?ble-layer channel cooling plate is 20% ethylene glycol-water solution, the cooling performance is better than the other three coolants. Other channel cooling plates perform better with water as the coolant.

Thermal performance of wedge pile slab foundation without frost protection insulation and highly insulated slab on ground floor – first year measurements

In the Nordic countries frost insulation is necessary if the foundation is above the frost-free depth. The thermal performance of the pile foundations is between a shallow ground foundation and a frost wall foundation. The pile ends extend below the frost line to help insulate the ground beneath a building’s foundation. The ends of the piles extend below the frost line to prevent the foundation of the building from frost heaving. However, there may be a risk that the ground below the slab on ground may freeze and frost heaving may occur there. The risk of frost below the slab on ground floor and/or basement increases because increasing thickness of floor insulation remarkable influences frost insulation dimensioning. In this study a 6.5 × 17-meter size uninsulated wedge pile slab foundation with highly insulated (U=0.07 W/(m2·K)) slab on ground floor was constructed for a heated building and equipped with temperature, soil moisture, relative humidity, and heat flux sensors. Seven temperature measurement piles below the building and one for reference 8 meters far from the building reached a depth of up to 3.2 meters, which is deeper than the usual 1.4 m depth to avoid freezing in foundation design. In three places, the temperature below the insulation of slab on the ground is measured at 0.5 meters step up to 3 meters from the outer wall of the building. The first-year measurement results showed that temperature did not drop below the zero degree below the foundation and floor. Even though during winter the daily average absolute minimum temperature was -24 °C the sum of degree hours below the zero degree was -7300 °Ch. The historic 50-year absolute sum of minimum degree hours below the zero degree was -28600 °Ch. In addition to real measurement results this three-dimensional temperature sensor field helps to calibrate and validate dynamic model for temperature simulation of thermal performance of wedge pile slab foundation without frost protection insulation and highly insulated slab on ground floor.

Heat Mitigation Benefits of Urban Trees: A Review of Mechanisms, Modeling, Validation and Simulation

Modeling, validating, and simulating are three essential parts in investigating the heat mitigation benefits of urban trees (BUT). Therefore, 81 relevant studies from the last ten years are reviewed, analyzed, and summarized in this study. Three main ways for urban trees to adjust the environment are summarized, including shade creation and radiation modification, cooling effects of transpiration, and airflow blocking and modification effects. Research works are analyzed with regard to four categories: (1) heat and moisture exchange mechanisms and their mathematical modeling; (2) verification of modeling predictions based on measurements; (3) thermal performance simulation and prediction; and (4) environmental assessment and human thermal comfort analyses. Future research opportunities are discussed: (1) conduct real-time and in-depth measurements to analyze the mechanisms of heat and moisture transfer of trees in different areas; (2) develop tree radiation attenuation, airflow resistance, and transpiration models to accurately describe heat and moisture transfer processes in the urban environment; and (3) establish a three-dimensional numerical simulation method that can accurately simulate the urban thermal environment with trees. This review provides researchers with an overview and potential research opportunities on the thermal effects of urban trees.

Climatic conditions as a guideline to mass customisation in Brazilian housing

Reducing the housing deficit is a vital issue to be addressed in developing countries. Although government programmes in Brazil aim to reduce it, there is criticism regarding the housing design, especially about their poor thermal performance. Guaranteeing high levels of thermal performance in affordable housing is expected to improve occupants’ satisfaction and reduce energy consumption. Therefore, this article aims to propose a system to develop solutions for designing a housing-unit module that enables adaptation to climate, topography, and site plan, as well as flexibility regarding expansions and changes in the pattern of use. Guidelines were created to develop the adaptable housing unit framework, which was programmed in Grasshopper to allow parametric design. One of the possible compositions was simulated using EnergyPlus and Ladybug Tools to determine suitable envelope characteristics for different climates. This process relied on multicriteria analyses to determine the best solution considering cooling and heating degree hours. Thermal performance simulation results show that the envelope solution for Florianópolis differs from that for São Joaquim, even with the same shape composition. While Florianópolis has lower wall absorptance and brick walls as the best solution, São Joaquim requires insulated walls and higher wall absorptances. The main conclusion is that such a framework is more feasible than a single solution because the design might be adapted according to problems identified a priori. This outcome is expected to guide practitioners toward sustainable development, considering the vital role that affordable housing plays in Brazil.

Quantitative review on recent developments of flat-plate solar collector design. Part 1: Front-side heat loss reduction

Several studies demonstrated novel and effective design solutions for the FPC thermal performance enchantment by the front side heat loss reduction. However, these design improvements were tested under different climatic and operating conditions. This fact makes it almost impossible to compare these design improvements. The following study quantitatively analyses the current flat-plate solar collector design developments, focusing on reducing front-side heat loss. It also performs a simulation analysis to demonstrate the thermal performance improvement of the chosen design solutions for three specific applications. The literature review was performed to identify the most promising design solutions. Then, the considered design solutions were modelled using the validated detailed theoretical model of a flat-plate solar collector (FPC). Finally, the modelling results were used to perform the thermal performance simulation analysis for Würzburg (Germany) climatic conditions and constant mean fluid operating temperatures of 50, 75, and 100 °C. The simulation results indicated that applying the considered design solutions to decrease the front-side heat losses could significantly increase the FPC thermal performance. Moreover, for high-temperature applications, where the front-side heat loss is a crucial factor determining the FPC thermal performance, there is more than a significant potential for the FPC thermal performance enchantment. To sum up, our findings indicate a significant thermal performance improvement potential that could increase the application range of FPCs and make them more competitive for a broader application area.

Validated simulation of thermal performance of phase change material infused recycled brick aggregate in 3D printed concrete

Passive design solutions are important in reducing the amount of heating and cooling energy required to maintain thermal comfort inside a building, without adding to the problem of climate change. Phase change materials (PCMs) are a thermal energy storage passive design solution, with the ability to change phase and store heat at chosen temperatures. PCMs can be added to concrete to create PCM-concrete, a composite material with sensible and latent heat storage ability. The purpose of this research is to create an accurate 2D model which can be used to determine the heat transfer through 3D printed concrete (3DPC) building façades containing PCM. Two building façade wall sections are simulated in ABAQUS and validated by thermal tests – a reference 3DPC façade section, in which 64% of the natural aggregate is replaced with recycled brick aggregate (RBA-3DPC), and a PCM-3DPC façade section, containing the same replacement level of RBA but with PCM vacuum impregnated into the RBA. With the validated model, computational simulations of the thermal performance of the PCM-3DPC façade section with varying PCM melting temperatures and different façade surface colours are tested. Subsequently, a PCM-3DPC façade section with 100% replacement of natural aggregate with RBA, infused with PCM of two melting temperatures (such as 18 °C for activation in winter and 28 °C for activation in summer) is proposed for climates with large seasonal temperature changes. In addition, contrary to most studies, an iterative approach was used for modelling cavity convection and internal ambient temperature, and this approach is found to be necessary, so as not to over constrain the model with set façade and internal temperatures.

Housing Adaptations to Climate: Vernacular Settlements on the Kahayan Riverbank at Palangka Raya, Indonesia

Producing buildings that can adapt to climatic conditions is one of the notable abilities of people who improve the quality of their houses. Lake Tundai is a residential area in Palangka Raya, Indonesia, occupied by a fishing community, isolated and only accessible through the Kahayan River. People prefer wood materials for house construction, and with a largely impoverished population, they remain in those houses they have inherited from the past. However, it is an example of a village resistant to the effects of global climate change, because their houses are climate-friendly, although natural breeze is the only thermal comfort enjoyed by the inhabitants of Lake Tundai. Using thermal performance simulation on the Tundai Lake houses, this research presents four types applied to four variable elements through the Ecotect analysis program to ascertain how the houses deal with the climate. Based on the climatic conditions in Lake Tundai. Type 2 with stilts, light roof, light walls, single ventilation, and ceiling is the most suitable model condition in Tundai Lake. The research concluded in 2023 that the influence of the building floor height from the ground may affect the thermal comfort in the room. If the floor height over the water level is below 1.2 meters. This study proposes an example of housing adaptation using wood materials nearby the water.

Simulation and Field-Based Study of Thermal Performance of a Building - A Case Study

Concerns about building thermal performance and energy consumption are fast growing as they account for roughly 40% of worldwide annual energy use. Building construction in Nepal is controlled by the National Building Codes (NBC), which focus solely on structural considerations and ignore thermal behaviour. As a result, housing tends to be too much warm and too cold during summer and winter respectively due to the lack of passive heating and cooling mechanisms considered during the construction phase. The Thakle Integrated Settle (TIS), built by the Department of Urban Development and Building Construction (DUDBC) under the National Reconstruction Authority and supported by Oxfam Nepal, was the subject of this research. The building’s performance in the chosen location was analysed using a field and TRNSY simulation-based technique. Using meteorological data from Meteonorm software, the TRNSYS model was created to examine the performance in terms of internal air temperature and heating/cooling load of two buildings with different orientations, e.g., North-East (NE) and South-West (SW). According to simulation results, there is a heating demand that covers roughly 37% of the year, while cooling and comfort conditions were 32% and 31%, respectively. For NE and SW-facing buildings, heating demand was 4.10 MWh and 4.07 MWh, while cooling demand was 1.302 MWh and 1.309 MWh respectively.

Simulation and optimization of thermal performance in diverging/converging manifold microchannel heat sink

Increasing complexity of electronic devices and chips places increasingly stringent requirements on heat sinks. A novel manifold microchannel heat sink with diverging/converging channels is proposed to improve heat transfer performance. The flow and heat transfer characteristics under single-phase are investigated numerically. The effects of two key parameters, manifold inlet to outlet ratio α and channel inlet to outlet ratio β, and their combinations on the thermal-hydraulic performance are explored. The results show that, in the single parameter optimization, a moderately diverging manifold layout and a converging channel layout each have the best enhancement effect on heat transfer for given pumping power, reducing the thermal resistance by 11.1% and 13.5% than homogeneous structure, respectively. When both parameters are set as optimization variables, the parameter combinations with enhanced performance are distributed in a sloping downward band in the parameter diagram. The configuration with α = 1/9 and β = 9 has the best reinforcement effect, reducing the thermal resistance by 19.18% for a given pumping power of 5×10−4 W. In addition, the heat transfer characteristics of the optimum and original configurations under non-uniform heating flux are also investigated for application, with the optimum configuration showing better performance at both temperature level and temperature uniformity.

Investigation of decoupling of thermal and electrical performance of semi-transparent photovoltaic windows based on the external quantum efficiency

Semi-transparent photovoltaic (STPV) windows have great potential in buildings energy saving due to their power generation and reduction of buildings energy consumption. STPV windows have a complex optical-thermal-electrical coupling mechanism. However, previous studies have rarely considered the coupling mechanism when simulating the thermal and electrical performance of STPV windows, which has resulted in the power generation being incorrectly treated as waste heat. As has been mentioned in EN 50583:2016 and IEC 63092:2020, the calculation of thermal performance of STPV windows should consider the mechanism that part of absorbed solar energy is transformed into electricity rather than heat. With considering the mechanism, based on the external quantum efficiency (EQE) of solar cells, a decoupled optical, thermal, and electrical performance simulation method for STPV windows was proposed in this study. Firstly, the optical characteristics of STPV windows and the EQE of the integrated solar cells were measured by a spectrophotometer and a monochromatic incident photon-to-electron conversion efficiency (IPCE) testing device, respectively. The EQE was used to calculate the spectral photoelectric conversion efficiency (SPCE) of STPV windows. Then, the SPCE was subtracted from the original absorptance and added to the front reflectance at corresponding wavelength, thereby decoupling the thermal and electrical performance. To verify the importance of the decoupling, the thermal and electrical performance of STPV windows with and without decoupling were investigated using EnergyPlus and WINDOW programs. An outdoor experimental rig was used to validate the simulation results of EnergyPlus, it was found that the decoupled results match well with experimental results. The simulation results show that in the coupled case, the window temperature and cooling load were overestimated, while the heating load was underestimated. However, the impact on power generation was negligible due to the low temperature coefficient of efficiency. Besides, for the analyzed STPV glazing configuration, the solar heat gain coefficient (SHGC) of the coupled case is relatively 9.3% higher than that of the decoupled case, when the solar cell coverage ratio is 70%. Moreover, the decoupled calculation method provides a theoretical basis for more accurate simulation and overall performance evaluation of STPV windows in maximum power point (MPP) state.

Thermal Performance Simulation of an LTCC Micro-Reactor for RT-PCR in Detection of SARS-Cov-2 Detection

In present paper, thermal simulation of LTCC based micro-chamber has been performed which is a key part of RT-PCR device. The RT-PCR device plays an important role in SARS-CoV-2 testing. The rRT-PCR system requires three different thermal cycles for DNA amplification which takes part in detection of SARS-CoV-2. The thermal cycle can be equipped using a heater structure in the chamber. A new LTCC based technique to develop micro-chamber has been designed and simulation has been performed using COMSOL to optimize thermal properties. Temperature distribution for a micro-chamber at three different voltages has been simulated. The temperature distribution is more uniform in micro-chamber with a buried metallic layer in comparision to micro-chamber without a metallic layer. The heater and temperature sensor were located outside the reaction chamber. A platinum based pattern as PTC temperature sensor is used in temperature measurement.

Simulation of Thermal Performance in a Typical Chinese Solar Greenhouse

A Chinese solar greenhouse (CSG) is used as a horticultural facility that provides high efficiency thermal storage performance to produce vegetables in winter. Quantifying the thermal performance of the surrounding structure including the back roof, soil, and north wall is helpful to improve the thermal performance of the CSG. The objectives of this study were to evaluate the performance of the heat transfer inside a CSG and analyze the thermal characteristics of different parts of the surrounding structures including solar gain, heat flux, and conduction heat transfer. The model was validated using experimental data from clear days and cloudy days during winter in Shenyang City, Liaoning Province, China. It indicates that the calculation method and model is valid and that EnergyPlus, which has been used in the thermal building field, can be used as a design tool to optimize solar energy storage and structure of greenhouses. The minimum temperatures of all components inside the CSG were maintained over 5 °C, even when the outside temperature reached to −22 °C, which showed good heat preservation in cold weather. Soil received the most radiation heat compared with other surfaces inside the CSG and contributed heat to the interior air to maintain air temperatures during the night.

Estimating Functional and Physical Service Life of Timber Buildings Concerning Thermal Performance Simulations

Currently, the cities in southern region of Chile present extremely high levels of atmospheric pollution. One of the main reasons for that is the adoption of inadequate thermal envelopes, which are not adapted to the buildings’ climatic and environmental surrounding conditions. Usually, the existing buildings do not have any type of thermal insulation, which causes excessive heating of spaces, in a region where the main source of heat is firewood. Thus, there is a need to intervene, improving the thermal energy performance of timber buildings, but will it be possible to make technically informed decisions that consider buildings’ service life? In this study, 72 buildings in the cities of Valdivia and Niebla (South Chile) have been analysed based on in-situ visual inspections. Concerning the novelty of the study, two methodologies have been used to define the end of their physical and functional service life, establishing a hierarchical scale concerning the priority of intervention in timber buildings. After that, three different thermal energy insulation performance scenarios have been modelled in terms of evaluating current conditions, basic thermal rehabilitation, or deep thermal rehabilitation. A more effective and profound intervention in terms of thermal performance leads to better habitability conditions for the buildings’ occupants in the context of South Chile, increasing their comfort between 36% to 46% of the year, when compared with current conditions. This kind of innovative analyses are extremely significant for the implementation of preventive maintenance programs focused not only on the restoration of the physical or functional service life of building stocks, but also considering their thermal energy performance in order to improve the habitability of the buildings for their occupants, and reducing both atmospheric pollutants and firewood consumption in the South of the country.

Thermal Optimization of Additively Manufactured Lightweight Concrete Wall Elements with Internal Cellular Structure through Simulations and Measurements

Combining the additive manufacturing (AM) process of extrusion with lightweight concrete, mono-material but multi-functional elements with an internal cellular structure can be created to achieve good thermal performance of a wall at low resource consumption. The aim of this paper is to analyze and optimize the actual thermal performance of such a component. A sensitivity analysis and a parametric optimization were conducted based on a mathematical description of heat transfer in cellular structures. To investigate the thermal performance, 2D and 3D heat transfer simulations were used and validated by heat flux measurements on an existing prototype. A geometric optimization led to a further reduction of the U-value by up to 24%, reaching 0.58 W/m2 K. The ratio of solid material to air inside the cells (relative density) was identified as the main driver, in addition to cell diameter, cell height, and cell wall thickness. The comparison of analytical and numerical results showed high correspondence with deviations of 3–10%, and for the experimental results 25%. These remaining deviations can be traced back to simplifications of the theoretical models and discrepancies between as designed and as built. The presented approach provides a good basis for optimizing the thermal design of complex AM components by investigating practical thermal problems with the help of 2D and 3D simulations, and thus offers a great potential for further applications.

Numerical simulation of thermal performance of bionic waste heat utilization equipment filled with nanofluids

Numerical simulation of thermal performance of bionic waste heat utilization equipment filled with nanofluids